Quote:
Originally Posted by Brian R Pateman
It's nice to see them displayed on a top class television too.
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Yes, it is certainly a very grand set and the sole reason I needed a Teletext Generator at all, as it's the only vintage Teletext set I have. A Viewdata generator (probably just as a software app) with connection via modem is is the next task.
Quote:
Originally Posted by terrykc
Absolutely fantastic!
One observation - I would have preferred a more optimistic weather forecast ...
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Thanks. Sorry about the weather outlook. It took me about 6 hours to re-code that page back into 7 bit ascii from a .gif of the original and, to be honest, the actual forecast wasn't the highest priority in my mind
Quote:
Originally Posted by terrykc
This reminds me of a Philips pattern generator we had in the late 80s which generated a teletext test page using only one line per field!...
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IMOGen puts out 12 lines per field, so the page counter between page selections moves like a blur! I was a little concerned at first as to whether so many lines would be tolerated by such an early decoder as is in the G11, but it deals with it without issue.
IMOGen now uses 6 separate switchable VBIs per frame/PROM, which is 72 stored data lines. These separate VBIs are 'paged' in and out in a sequence controlled by the CPLD. Sequencing VBIs within individal PROMs and across multiple PROM sets was quite a challenge with a mere 64 macrocell CPLD - I ended up using 63 of the available macrocells in the end, although it was the whole 64 in one version. Creating the PROM images to maintain correct page numbering and subcarrier/burst phase throughout all this sequencing and paging also took some work.
Quote:
Originally Posted by terrykc
I recalled a bit of the Broadcast Teletext Specification which, as far as I know, anybody has ever used, which says that rows can be transmitted in any order.
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Well yes, as long as you keep a track of where your header rows are inserted. One out of sequence data line on the wrong side of a header row and it all goes to pot!
Quote:
Originally Posted by Tazman1966
I look forward to the update when I can get myself and the unit round to your place.
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Yep, I'll sort that out asap. I've got some new, different, buttons on order too
